Instrument for distributing restorative material on a tooth surface

ABSTRACT

A dental instrument with interchangeable roller tips for distributing restorative materials on a tooth surface quickly, precisely and homogeneously with little adherence of the restorative material to the instrument. The instrument has an elongate body with a handle portion and one or two working ends extending therefrom with a roller tip rotatably mounted on each working end. The roller tip may be removable from the working end, such that differently shaped tips may be used interchangeably during the restoration of the tooth, as necessary. The roller tip may rotate directly about the working end, or alternatively, a bushing or bearing may be rotatably mounted on the working end between the working end and the roller tip, such that the roller tip is rotatable on the working end by means of the rotatable bushing or bearing.

FIELD OF THE INVENTION

This invention relates to a dental instrument for homogeneously applyingand shaping tooth restorative material, and specifically, a dentalinstrument with interchangeable roller tips for distributing therestorative material.

BACKGROUND OF THE INVENTION

Composite materials, i.e., tooth restorative materials containingbinders in the form of hardenable, generally organic substances, havebecome the standard filling materials in dentistry. A disadvantage ofthese composite materials, however, is their tendency to adhere more orless to the instrument that is used to apply or shape them. As a result,and by way of example, the composite material has a tendency to be drawnoff from the edges of the cavity, to be distributed inhomogeneously onthe tooth surface, and to form air bubbles during the distribution. Theinstruments used for distributing the restorative material typicallycomprise a steel instrument with an uncoated working tip portion or atip portion coated with TiNi, for example, or a plastic material with orwithout a coated or treated working tip portion. As a further example,the adhesion of the composite material to the instrument has beenadjusted by coating the working ends of the instrument with Teflon™, butthese instruments have limited shapes and are not always satisfactory inpractice. Another solution is proposed in U.S. Pat. No. 6,071,122,wherein the working tip of the plastic instrument has a discontinuoussurface that includes an array of micropits. While that instrumentachieves reduced adhesion of the composite material, homogeneousdistribution free of air bubbles has not yet been fully achieved. Thereis thus a need to develop a dental instrument that is effective indistributing homogeneously a composite restorative material to a toothsurface, and which avoids the integration of air bubbles in therestorative.

SUMMARY OF THE INVENTION

The present invention provides a dental instrument with interchangeableroller tips for distributing restorative materials on a tooth surface,which roller tips distribute the restorative material quickly, preciselyand homogeneously with little adherence of the restorative material tothe roller tip due, in part, to the short contact time between theroller tip and the composite material. To this end, a dental instrumentis provided having an elongate body with a handle portion and a workingend extending therefrom. A roller tip is rotatably mounted on theworking end so as to rotate about a center axis of the end of theinstrument, and is sized to distribute the restorative material on atooth surface, including a cavity surface. The roller tip is removablefrom the working end, such that differently shaped tips may be placed onthe working end during the restoration of the tooth, as necessary, toensure complete and even coverage to an uneven surface. In an exemplaryembodiment, a bushing or rolling element bearing is rotatably mounted onthe working end between the working end and the roller tip, such thatthe roller tip is rotatable on the working end by means of the rotatablebushing or bearing. In another exemplary embodiment, the dentalinstrument includes two working ends extending in opposing directionsfrom the handle portion to provide different angles for the working endsor to provide differently shaped roller tips on the working ends.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description given below, serve to explain the invention.

FIG. 1 is a perspective view of a dental instrument of the presentinvention;

FIG. 2 is a cross-sectional view of a first working end of theinstrument of FIG. 1, as taken along line 2-2;

FIG. 2A is a cross-sectional view of an alternative embodiment of thefirst working end of the instrument of FIG. 1, also taken along line2-2;

FIG. 3 depicts a side elevational view of an alternative embodiment of adental instrument of the present invention with the working end inpartial cross-section;

FIGS. 4A-4C depict various embodiments for the roller tips of theinstrument of the present invention; and

FIGS. 5A-5B depict uses of an instrument of the present invention inapplying and shaping restorative materials on tooth surfaces.

DETAILED DESCRIPTION

Reference will be made to FIGS. 1-5B in which like reference numeralsare used to refer to like parts. An exemplary dental instrument 10 ofthe present invention is depicted in perspective view in FIG. 1.Instrument 10 is uniquely designed for distributing tooth restorativematerials on a tooth surface within the oral cavity of a patient, i.e.within the patient's mouth, without the adherence problems of the priorart. Instrument 10 is also designed for distributing tooth restorativematerials on an artificial tooth surface to form a prosthetic tooth.Instrument 10 has an elongate body 12 with a first working end 14 and asecond working end 16 that extend from opposite ends 18 a, 18 b of ahandle portion 18. As shown in FIG. 1, the first working end 14 extendsfrom end 18 a of the handle portion 18 such that its center axis issubstantially coaxial with the center axis of the handle portion 18.This construction may be referred to as an axial working end. As furthershown in FIG. 1, the second working end 16 extends from end 18 b of thehandle portion 18 in a direction such that its center axis isperpendicular (90°) to the center axis of the handle portion 18. Thisconstruction may be referred to as a right angle working end. Dependingon the tooth to be restored, differently angled working ends allow thedentist to choose the appropriate angle for most effectivelydistributing the restorative material on the tooth surface, particularlywhere the tooth surface is located in the oral cavity. While the secondworking end 16 is shown at a 90° angle from the center axis of thehandle portion 18, it may be appreciated that angles in the range of5-90° may be useful and angles in the range of 45-90° may be even moreuseful. In addition, both working ends 14, 16 may be coaxial with thecenter axis of the handle portion 18 or both ends 14, 16 may be angledrelative to the center axis of the handle portion 18. Thus, theparticular angles for the first and second working ends 14, 16 depictedin FIG. 1 are not intended to limit the configuration of the instrument10 of the present invention.

Each of the first and second working ends 14, 16 are depicted with aroller tip 20, 20 a, respectively, sized to distribute restorativematerial on a tooth surface, wherein tips 20, 20 a are removable fromthe first and second working ends 14, 16 and interchangeable with eachother or with other roller tips 20. An exemplary embodiment of theroller tip 20 is more clearly depicted in cross-sectional view in FIG.2, as taken along line 2-2 of FIG. 1. The first working end 14 is shownhaving a reduced diameter as compared to the diameter of the remainingportion of the elongate body 12, including handle portion 18, but theinvention is not so limited. In this embodiment, mounted on the firstworking end 14 is a bushing 30, which is rotatable on the first workingend 14 about the center axis of the first working end 14. The roller tip20 is mounted on, and rotatable with, the bushing 30 so as to berotatable about the first working end 14 by means of the rotation of therotatable bushing 30, which rotates relative to working end 14. Becausethe center of the roller tip 20 is coaxial with the center of theworking end 14 of the instrument 10 in this exemplary embodiment, torqueis avoided during rotation of the roller tip 20 to distribute therestorative material. While the roller tip 20 is depicted as a closedcylinder at distal end 15, it may be appreciated that the roller tip 20may be an open cylinder at distal end 15 thereby exposing the bushing30. However, the exemplary embodiment shown in FIG. 2 is advantageous inthat it prevents restorative material from entering into the bushingarea and interfering with operation of the rotatable tip 20 and bushing30. Roller tip 20 is further shown having a substantially uniformlycylindrical surface 22 for distributing restorative material on a toothsurface. It may be appreciated, however, as will be discussed in moredetail below, that roller tip 20 may be shaped to have a non-uniformouter surface 22.

In an exemplary embodiment, bushing 30 includes a clip portion 32 forengaging a ridge portion 13 of first working end 14. Clip portion 32prevents restorative material from getting between the bushing 30 andthe first working end 14. Clip portion 32 further assists in theretention and easy removal of the roller tip 20 such that the roller tip20 is interchangeable with other roller tips. A bulbous shape for topportion 31 of bushing 30 is also advantageous in that it also assists inthe interchangeability of roller tip 20 without the risk of axialdisassembling. A similar construction for bushing 30 may be used atsecond working end 16.

Advantageously, the elongate body 12, including first and second workingends 14, 16 and/or bushing 30, comprise a plastic material containing afriction-reducing additive to facilitate rotation of the bushings 30around the first and second working ends 14, 16. Friction is the forcethat retards, that is partially brakes, the movement of two surfacesagainst each other, and the kinetic coefficient of friction, μ, is ameasurement of the extent of friction present during rotation. Thekinetic coefficient of friction is measured by dividing the frictionalresistance force, f, by the normal force, N, that presses the twosurfaces together when they move relative to each other. Advantageously,the amount of friction-reducing material in one or both of the elongatebody 12 and bushings 30 is sufficient to provide a kinetic coefficientof friction of less than 0.2 between the first working end 14 and thebushing 30 on which the roller tip 20 is mounted, and between the secondworking end 16 and the bushing 30 on which roller tip 20 a is mounted.

In an exemplary embodiment, the elongate body 12 comprises a plasticmaterial containing 2-30 wt. % of a friction-reducing additive. Inanother exemplary embodiment, the bushings 30 comprise a plasticmaterial containing 2-30 wt. % of a friction-reducing additive. In yetanother exemplary embodiment, each of the elongate body 12 and thebushings 30 comprise a plastic material containing 2-30 wt. % of afriction-reducing additive. In each of these exemplary embodiments, thefriction-reducing additive is advantageously polytetrafluoroethylenepresent in an amount of 2-20 wt. %, and more advantageously, thepolytetrafluoroethylene is present in an amount of 5-15 wt. %. Inaddition to or in place of polytetrafluoroethylene as afriction-reducing additive, and by way of example only, fluorinatedethylene propylene, perfluoroalkoxy copolymers, carbon fibers andmolybdenum disulfide may be also be effective to provide a lowcoefficient of friction. Similar to the polytetrafluoroethyleneadditive, the fluorinated ethylene propylene and perfluoroalkoxycopolymers are advantageously present in an amount of 2-20 wt. % of theplastic material, while carbon fibers are advantageously present in anamount of 5-30 wt. % of the plastic material and molybdenum disulfide isadvantageously present in an amount of 3-6 wt. % of the plasticmaterial. It may be understood, however, that other now known orhereafter developed friction-reducing materials may be used as anadditive in accordance with the present invention in an appropriateand/or similar amount to achieve a low-frictional resistance between therotating components.

The plastic material for the elongate body 12 is advantageously one or acombination of polyetherimide, polybutylene terephthalate,polyphenylsulfone, polyethersulfone, polyphthalamid (PA6T/6I), andpolyetheretherketone. To increase the stiffness of the elongate body 12,the plastic material may be reinforced with glass fibers or carbonfibers. The friction-reducing additive may be compounded within theplastic matrix to form a plastic material charged with thefriction-reducing additive to reduce the friction with the rotatingbushing 30. Alternatively, the first and second working ends 14, 16 ofthe elongate body 12 may be coated with the friction-reducing additive.Thus, the plastic material containing the friction-reducing additiveencompasses both a plastic matrix with a friction-reducing additivedispersed therein or a plastic body with the surface thereof coated witha friction-reducing additive.

The plastic material for the bushing is advantageously an acetyl resin,but the invention is not so limited. Advantageously, thefriction-reducing additive is compounded within the plastic matrix toprovide the low friction resistance. While coating an inside surface ofthe bushing 30 with the friction-reducing additive is not precluded fromthe present invention, it may be appreciated that the small size of thebushings 30 limit the practicality of this approach.

The roller tips 20, 20 a advantageously comprise a resilient materialthat has the ability to return to its original shape after a mechanicalcompression, with no plastic deformation occurring when subjected tomechanical stress under normal circumstances. Roller tips 20, 20 a alsoadvantageously comprise a material having low surface energy, forexample, less than 25 mN/m, which also contributes to low adhesion withthe restorative composite materials. Examples of such resilientmaterials include silicones, polyurethanes, and thermoplasticelastomers. Advantageously, roller tips 20, 20 a comprise afluorine-charged thermoplastic vulcanizate, such as the Viton®fluoroelastomers from DuPont Dow Elastomers, Wilmington, Del. andFluoroprene® from Freudenberg-NOK, Plymouth, Mich., which each contain40-70 wt. % fluorine. These fluorine charged materials have low surfacetension, on the order of 18-20 mN/m, and thus, have low adhesion to therestorative composite materials. In an exemplary embodiment, the rollertip material has a Shore A hardness of 20-60, and more advantageously,the roller tip has a Shore A hardness on the order of 30. The roller tipmaterial may be a solid material or a microporous material. Because theroller tips 20, 20 a are interchangeable on the working ends 14, 16 ofinstrument 10, various roller tips 20 may be provided having differenthardnesses, different shapes and different colors, as desired.

The bushings 30 may be pre-mounted inside the roller tips 20, 20 a toprovide units that are then mounted on the working ends 14 and 16 of theelongate body 12 to form the instrument 10, and the units areinterchangeable. Alternatively, the bushings 30 may be pre-mounted onthe working ends 14 and 16, and the roller tips 20, 20 a areinterchangeably mounted on the pre-mounted bushings 30. In eitherembodiment, the roller tips 20, 20 a may be pre-molded and flexibleenough to be mounted on the bushings 30 without difficulty.Alternatively, when the roller tips 20, 20 a and bushings 30 arepre-mounted to form units, the roller tips 20, 20 a may be over-moldedonto the bushings 30, such as where the material of the roller tips isnot flexible enough to be easily mounted on the bushings 30.Advantageously, as depicted in FIG. 2, the roller tip 20 is shorter thanthe bushing 30 to provide clearance between roller tip 20 and elongatebody 12 to avoid friction between the two.

FIG. 2 depicts in cross-sectional view an alternative embodiment of theinstrument of the present invention in which a rolling element bearing34 is mounted on working end 14 instead of bushing 30. Rolling elementbearing 34 includes rolling elements 36, such as ball bearings,cylindrical rollers or taper rollers, positioned and rotatable betweenan outer ring 38 and an inner ring 39. The rolling element bearing 34may also be used on working end 16 in place of bushing 30. Thedescription above regarding the materials, construction, and mounting ofbushing 30 apply equally to rolling element bearing 34.

FIG. 3 depicts in partial cross-section another exemplary embodiment ofa dental instrument 10′ of the present invention having an elongate body12 with a handle portion 18 and a single working end 14 extendingtherefrom. Thus, dental instruments in accordance with the presentinvention may have one or two working ends. In FIG. 3, there is alsodepicted an embodiment in which the bushing 30 (or rolling elementbearing 34) is eliminated, such that the roller tip 20 is directlyrotatable about the working end 14. To achieve low friction resistancebetween the roller tip 20 and the working end 14 of the elongate body12, the elongate body 12 comprises a plastic material containing afriction-reducing additive, as discussed above in reference toinstrument 10. If additional friction reduction is desired, the rollertip 20 can be gas-phase fluorinated. Thus, in this embodiment, ratherthan the roller tip 20 rotating via rotation of a bushing 30 (or rollingelement bearing 34), the roller tip 20 itself rotates directly relativeto the working end 14. Thus, an instrument of the present invention maybe provided with one or two working ends 14 and/or 16, and may beprovided with or without bushings 30 (or rolling element bearings 34).While the greatest friction reduction may occur with a plastic elongatebody 12 charged with a friction-reducing additive upon which is mounteda bushing(s) or bearing(s) charged with a friction-reducing additive, itmay be understood that the materials of these components may be alteredand/or the bushing(s)/bearing(s) eliminated as long as the kineticcoefficient of friction is less than 0.2 between the working ends 14, 16and the rotating component (roller tip 20, bushing 30, or rollingelement bearing 34).

FIGS. 4A-4C depict various shapes for the roller tips 20. While theroller tip 20 on first working end 14 of FIGS. 1-3 was depicted as beingsubstantially uniformly cylindrical along its outer surface 22, FIG. 4Adepicts a drop-shaped or pear-shaped roller tip 20 a, also shown onsecond working end 16 in FIG. 1, where the outer surface 22 a has amaximum circumference 24 a adjacent the handle portion 18, and thensharply tapers inward to an intermediate circumference 26 a from whichit then tapers less drastically to a distal tip 28 a furthest from thehandle portion 18, thereby forming a very small circumference distal tip28 a that is adapted to fit within small cavities in a tooth surface(not shown). The drop-shaped roller tip 20 a in FIG. 4A provides thebenefit of the large maximum circumference surface 24 a for applying andshaping the composite material generally to the tooth surface, while thesmall distal tip portion 28 a ensures homogeneous distribution intosmall irregularities in the tooth surface not reachable by the largerrolling surface 24 a. FIG. 4B depicts a tapered roller tip 20 b with arelatively small uniform taper angle such that the outer surface 22 bhas a maximum circumference 24 b adjacent the handle portion 18 and thenslightly tapers inward to a minimum circumference 28 b furthest from thehandle portion 18 to provide a larger distal tip portion 28 b that isadapted to engage larger irregularities in the tooth surface. FIG. 4C issimilar to FIG. 4B but depicting a larger uniform taper angle from themaximum circumference 24 c such that the distal tip 28 c is smaller indiameter. All statements made herein regarding roller tip 20 are equallyapplicable to roller tips 20 a, 20 b and 20 c, for example, statementsregarding the material of construction or method of mounting.

The dentist may interchange these roller tips 20, 20 a, 20 b, 20 c, asdesired, to provide the working ends 14, 16 with shapes most suitablefor the particular tooth surface being restored. For example, instrument10 of FIG. 1 may be provided with additional roller tips 20 b, 20 c thatare removably mountable on working ends 14, 16 upon removal of rollertips 20, 20 a such that all roller tips 20, 20 a, 20 b, 20 c are fullyinterchangeable. The additional roller tips 20 b, 20 c may bepre-mounted on bushings 30 or bearings (not shown) for embodiments inwhich the roller tips 20, 20 a are substantially permanently mounted onbushings 30 (or roller element bearings 34), and the bushings 30(bearings 34) are removably mounted on the working ends 14, 16.Alternatively, additional roller tips 20 b, 20 c may be removablymountable directly on the working ends 14, 16 for those embodimentswhere no bushings or bearings are used, or removably mountable onbushings 30 (or roller element bearings 34) that are pre-mounted on theworking ends 14, 16. It may be appreciated that other roller tip shapesmay be utilized for the instrument 10 (or 10′) of the present inventionother than those depicted in FIGS. 1-4B.

As a result of the interchangeable roller tips 20, 20 a, 20 b, 20 c, thedental instrument of the present invention is particularly suitable foruse with both anterior and posterior teeth. By way of example, asubstantially uniformly cylindrical-shaped roller tip 20 depicted inFIGS. 1-3 may be ideal for distributing restorative material on thefront surface of an anterior tooth, while the drop-shaped andpear-shaped roller tips 20 a, 20 b, 20 c depicted in FIGS. 4A-4C may beparticularly suitable for anterior proximal surfaces and for thesurfaces of proximal teeth, in particular on the marginal area and thecavity walls of a posterior tooth.

FIGS. 5A and 5B depict the benefit of the instrument 10 (or 10′) of thepresent invention in distributing restorative material onto a toothsurface in the oral cavity. In FIG. 5A, a roller tip 20 with asubstantially uniformly cylindrical outer surface 22 is mounted on anaxial working end 14, i.e., the working end 14 has a center axis coaxialwith the center axis of the handle portion 18, as shown in FIG. 1. Arestorative material 40 is distributed on a front tooth surface 50 bymanipulating the instrument 10 to roll the roller tip 20 across thetooth surface 50, back and forth as necessary, to provide a homogeneousand relatively flat layer of restorative material that is free ofbubbles. The homogeneity and bubble-free nature are due to the quickdistribution achievable by means of the rotating roller tip 20 wherebyadherence of the restorative material 40 to the surface 22 of the rollertip 20 is reduced or avoided. “Distribution” as referred to herein mayinclude the initial application of the restorative material 40 to thetooth surface 50, as well as the spreading, shaping, adapting and/orsmoothing of the material 40 into a uniform layer. Alternatively, therestorative material 40 may be first introduced onto the tooth surface50 by other means, and distribution with the instrument 10 (or 10′) ofthe present invention may include the spreading, shaping, adaptingand/or smoothing of the material 40 into a uniform layer. Thus, theterms “distributing” and “distribution” are intended to be broad inscope, referring to any application and/or manipulation of therestorative material relative to the tooth surface. Likewise, “toothsurface” broadly refers to any external surface of the tooth or anyinternal surface, such as the walls of a tooth cavity. By virtue of theroller tips 20 (20 a, 20 b, 20 c), instrument 10 (or 10′) of the presentinvention is also particularly useful in creating a defined layerthickness of restorative material on a tooth surface.

FIG. 5B depicts use of an instrument 10 (or 10′) of the presentinvention for distributing restorative material 40 on a posterior toothsurface 60, both on the marginal area and on the cavity walls. Thedrop-shaped roller tip 20 a depicted in FIG. 4A is mounted on a rightangle working end 16 of the elongate body 12, i.e., the center axis ofthe working end 16 is angled 90° relative to the center axis of thehandle portion 18, as shown in FIG. 1. The distal tip 28 a of the rollertip 20 a is capable of distributing the restorative material 40 into thecavity 62 and forming a uniform or homogeneous layer on the cavitywalls, and the outer surface 22 a including the maximum circumference 24a to the intermediate circumference 26 a is effective to distribute therestorative material 40 on the marginal area. The restorative material40 does not stick to the instrument 10 because it does not have time toadhere completely to the tip surface 22 a due to the quick and efficientdistribution achieved by the roller tip 20 a. The quick and efficientdistribution also avoids the integration of air bubbles during thedistribution process.

The easy interchangeability of the roller tips 20, 20 a, 20 b, 20 c, aswell as a double-ended instrument 10 having differently shaped tips 20and 20 a (20 b or 20 c) provides the dentist with flexibility during thedistribution process. The control of friction between the roller tips 20(20 a, 20 b, 20 c) and the elongate body 12, or between the bushings 30and the body 12, enable the quick, smooth and efficient distribution.There is thus provided a dental instrument for distributing restorativematerial on a tooth surface that is far superior to the dentalinstruments of the prior art. Also, as stated previously, while thedental instrument 10 (or 10′) is particularly useful for distributingrestorative material on a tooth surface that resides in the oral cavity,the invention is not so limited. Dental instrument 10 (or 10′) may alsobe used to shape a prosthetic tooth. Thus, the roller tips 20 (20 a, 20b, 20 c) are sized for use with a tooth surface, including those ofnatural and artificial teeth residing in the oral cavity as well asartificial prosthetic teeth intended to later reside in the oral cavity.

While the present invention has been illustrated by the description ofone or more embodiments thereof, and while the embodiments have beendescribed in considerable detail, they are not intended to restrict orin any way limit the scope of the appended claims to such detail.Additional advantages and modifications will readily appear to thoseskilled in the art. For example, while the dental instrument of thepresent invention addresses shortcomings experienced in the distributionof composite-type restorative materials, the instrument may well findapplicability with other dental materials. The invention in its broaderaspects is therefore not limited to the specific details, representativeapparatus and method and illustrative examples shown and described.Accordingly, departures may be made from such details without departingfrom the scope or spirit of the general inventive concept.

1. A dental instrument for distributing a restorative material on atooth surface, the instrument comprising: an elongate body comprising ahandle portion and a first working end extending therefrom; and a firstroller tip rotatably mounted on the first working end and rotatableabout an axis of the first working end and sized to distribute arestorative material on a tooth surface.
 2. The dental instrument ofclaim 1 wherein the first roller tip is removable from the first workingend.
 3. The dental instrument of claim 2 further comprising at least oneadditional roller tip mountable on the first working end whereby the atleast one additional roller tip is interchangeable with the first rollertip.
 4. The dental instrument of claim 1 wherein the axis of the firstworking end is a center axis about which the first roller tip isrotatable.
 5. The dental instrument of claim 4 wherein the handleportion has a center axis and the center axis of the first working endis coaxial with the center axis of the handle portion.
 6. The dentalinstrument of claim 4 wherein the handle portion has a center axis andthe center axis of the first working end is angled 45-90° with respectto the center axis of the handle portion.
 7. The dental instrument ofclaim 1 wherein the elongate body comprises a plastic materialcontaining 2-30 wt. % of a friction-reducing additive.
 8. The dentalinstrument of claim 7 wherein the friction-reducing additive ispolytetrafluoroethylene.
 9. The dental instrument of claim 8 wherein theplastic material comprises 5-15 wt. % of a polytetrafluoroethylenefriction-reducing additive.
 10. The dental instrument of claim 7 whereinthe plastic material is selected from the group consisting ofpolyetherimide, polybutylene terephthalate, polyphenylsulfone,polyethersulfone, polyphthalamid and polyetheretherketone.
 11. Thedental instrument of claim 7 wherein the plastic material is reinforcedwith at least one of glass fibers and carbon fibers.
 12. The dentalinstrument of claim 1 wherein the elongate body comprises a plasticmaterial containing friction-reducing additive in an amount sufficientto provide a kinetic coefficient of friction of less than 0.2 betweenthe first working end and the first roller tip.
 13. The dentalinstrument of claim 1 wherein the roller tip comprises at least onematerial selected from the group consisting of: a silicone, athermoplastic elastomer, and polyurethane.
 14. The dental instrument ofclaim 1 wherein the roller tip has a Shore A hardness in the range of20-60.
 15. The dental instrument of claim 1 wherein the roller tip hasan outer surface that is substantially uniformly cylindrical.
 16. Thedental instrument of claim 1 wherein the roller tip has an outer surfacewith a maximum circumference adjacent the handle portion and an inwardtaper from the maximum circumference to a minimum circumference furthestfrom the handle portion.
 17. The dental instrument of claim 1 furthercomprising a bushing rotatably mounted on the first working end betweenthe first working end and the first roller tip whereby the first rollertip is rotatable relative to the first working end by means of therotatable bushing.
 18. The dental instrument of claim 17 wherein thefirst working end includes a ridge portion and the bushing includes aclip portion adapted to engage the ridge portion.
 19. The dentalinstrument of claim 1 further comprising a rolling element bearingmounted on the first working end between the first working end and thefirst roller tip whereby the first roller tip is rotatable relative tothe first working end by means of the rolling element bearing.
 20. Thedental instrument of claim 1 further comprising a second working end forinserting into an oral cavity and a second roller tip rotatably mountedon the second working end and rotatable about the axis of the secondworking end to distribute a restorative material on a tooth surface. 21.The dental instrument of claim 20 wherein the second roller tip isremovable from the second working end.
 22. The dental instrument ofclaim 21 further comprising at least one additional roller tip mountableon the first and second working ends whereby the at least one additionalroller tip is interchangeable with the first and second roller tips. 23.The dental instrument of claim 20 further comprising a bushing rotatablymounted on the second working end between the second working end and thesecond roller tip whereby the second roller tip is rotatable relative tothe second working end by means of the rotatable bushing.
 24. The dentalinstrument of claim 23 wherein the second working end includes a ridgeportion and the bushing includes a clip portion adapted to engage theridge portion.
 25. The dental instrument of claim 20 further comprisinga rolling element bearing mounted on the second working end between thesecond working end and the second roller tip whereby the second rollertip is rotatable relative to the second working end by means of therolling element bearing.
 26. A dental instrument for distributing arestorative material on a tooth surface, the instrument comprising: anelongate body having a first working end and a second working end, eachwith a center axis, and a handle portion located therebetween; a bushingrotatably mounted on each of the first and second working ends; and aroller tip mounted on each bushing and rotatable with the bushing aboutthe center axis of the respective first and second working ends, eachroller tip sized to distribute a restorative material on a toothsurface, wherein the roller tips are removable from the elongate body.27. The dental instrument of claim 26 wherein the handle portionincludes a center axis, and wherein the center axis of the first workingend is coaxial with the center axis of the handle portion and the centeraxis of the second working end is angled 45-90° with respect to thecenter axis of the handle portion.
 28. The dental instrument of claim 26wherein the elongate body comprises a plastic material containing 2-30wt. % of a friction-reducing additive.
 29. The dental instrument ofclaim 28 wherein the friction-reducing additive ispolytetrafluoroethylene.
 30. The dental instrument of claim 29 whereinthe plastic material comprises 5-15 wt. % of a polytetrafluoroethylenefriction-reducing additive.
 31. The dental instrument of claim 26wherein the bushing comprises a plastic material containing 2-30 wt. %of a friction-reducing additive.
 32. The dental instrument of claim 31wherein the friction-reducing additive is polytetrafluoroethylene. 33.The dental instrument of claim 32 wherein the plastic material comprises5-15 wt. % of a polytetrafluoroethylene friction-reducing additive. 34.The dental instrument of claim 26 wherein at least one of the elongatebody and the bushings comprises a plastic material containing afriction-reducing additive in an amount sufficient to provide a kineticcoefficient of friction of less than 0.2 between the first and secondworking ends and the respective roller tips.
 35. The dental instrumentof claim 34 wherein the friction-reducing additive ispolytetrafluoroethylene.
 36. The dental instrument of claim 26 whereinthe elongate body and the bushings each comprise a plastic materialcontaining a friction-reducing additive in an amount sufficient toprovide a kinetic coefficient of friction of less than 0.2 between thefirst and second working ends and the respective bushings.
 37. Thedental instrument of claim 36 wherein the friction-reducing additive ispolytetrafluoroethylene.
 38. The dental instrument of claim 26 whereinthe roller tips comprise at least one material selected from the groupconsisting of: a silicone, a thermoplastic elastomer, and polyurethane.39. The dental instrument of claim 38 wherein the roller tip has a ShoreA hardness in the range of 20-60.
 40. The dental instrument of claim 26wherein at least one of the roller tips has an outer surface that issubstantially uniformly cylindrical.
 41. The dental instrument of claim26 wherein at least one of the roller tips has an outer surface with amaximum circumference adjacent the handle portion and an inward taperfrom the maximum circumference to a minimum circumference furthest fromthe handle portion.
 42. The dental instrument of claim 26 wherein thefirst and second working ends each include a ridge portion and eachbushing includes a clip portion adapted to engage the respective ridgeportion.
 43. The dental instrument of claim 26 wherein the roller tipsare removably mounted on the bushings whereby the roller tips areremovable from the elongate body and the bushings.
 44. The dentalinstrument of claim 43 further comprising at least one additional rollertip removably mountable on the bushings whereby the at least oneadditional roller tip is interchangeable with the mounted roller tips.45. The dental instrument of claim 26 wherein the roller tips aresubstantially permanently mounted on the bushings and the bushings areremovably mounted on the first and second working ends such that theroller tips are removable with the bushings from the elongate body. 46.The dental instrument of claim 45 further comprising at least oneadditional roller tip substantially permanently mounted on a respectiveadditional bushing, wherein the respective additional bushing isremovably mountable on the first and second working ends whereby the atleast one additional roller tip and respective bushing areinterchangeable with the mounted roller tips and bushings.
 47. A dentalinstrument for distributing a restorative material on a tooth surface,the instrument comprising: an elongate body having a handle portion witha center axis, a first working end with a center axis substantiallycoaxial with the handle portion center axis, and a second working endwith a center axis angled 45-90° relative to the handle portion centeraxis, wherein the elongate body comprises a plastic material containingpolytetrafluoroethylene; a bushing rotatably mounted on each of thefirst and second working ends, wherein the bushing comprises a plasticmaterial containing polytetrafluoroethylene; and a roller tip mounted oneach bushing and rotatable with the bushing about the center axis of therespective first and second working ends, each roller tip sized todistribute a restorative material on a tooth surface, wherein the rollertips are removable from the elongate body.
 48. The dental instrument ofclaim 47 wherein the plastic materials of the bushings and the elongatebody each contain 2-20 wt. % polytetrafluoroethylene.
 49. The dentalinstrument of claim 48 wherein the plastic materials of the bushings andthe elongate body each contain 5-15 wt. % polytetrafluoroethylene. 50.The dental instrument of claim 47 wherein the elongate body and thebushings together comprise an amount of polytetrafluoroethylenesufficient to provide a kinetic coefficient of friction of less than 0.2between the first and second working ends and the respective bushings.51. The dental instrument of claim 47 wherein the roller tips compriseat least one material selected from the group consisting of: a silicone,a thermoplastic elastomer, and polyurethane.
 52. The dental instrumentof claim 51 wherein the roller tip has a Shore A hardness in the rangeof 20-60.
 53. The dental instrument of claim 47 wherein at least one ofthe roller tips has an outer surface that is substantially uniformlycylindrical.
 54. The dental instrument of claim 47 wherein at least oneof the roller tips has an outer surface with a maximum circumferenceadjacent the handle portion and an inward taper from the maximumcircumference to a minimum circumference furthest from the handleportion.
 55. The dental instrument of claim 47 wherein the first andsecond working ends each include a ridge portion and each bushingincludes a clip portion adapted to engage the respective ridge portion.56. The dental instrument of claim 47 wherein the roller tips areremovably mounted on the bushings whereby the roller tips are removablefrom the elongate body and the bushings.
 57. The dental instrument ofclaim 56 further comprising at least one additional roller tip removablymountable on the bushings whereby the at least one additional roller tipis interchangeable with the mounted roller tips.
 58. The dentalinstrument of claim 47 wherein the roller tips are substantiallypermanently mounted on the bushings and the bushings are removablymounted on the first and second working ends such that the roller tipsare removable with the bushings from the elongate body.
 59. The dentalinstrument of claim 58 further comprising at least one additional rollertip substantially permanently mounted on a respective additionalbushing, wherein the respective additional bushing is removablymountable on the first and second working ends whereby the at least oneadditional roller tip and respective bushing are interchangeable withthe mounted roller tips and bushings.